Originally Posted by danco The Twilight Zone
was there first:
"Back There," in which a man travels back in time and attempts to stop Lincoln's assassination, unsuccessfully. In fact, he's the one to give John Wilkes Boothe the idea in the first place...
There was even an episode of the terrible UPN version of TZ like this, where a woman goes back in time and decides she must commit an act of infanticide on baby Hitler. She finally does it, killing herself in the process, but the nanny decides to buy a homeless ladies baby as a replacement rather than informing the parents that their real baby has been killed, and of course this homeless baby had the genetic disposition to be prone to genocidal leanings or something.
There's also the Terminator movies... in the first one a soldier from the future is sent back to protect a young lady so she will give birth to a future leader and hero, and he winds up fathering the said leader and hero. In the sequel it is revealed that the remains of the first terminator was used to develop the AI technology that eventually runs amuck, so in a sense, the first terminator goes back in time and "fathers" the technology that spawned it.
Also La Jetee/12 Monkeys... more so with La Jetee because it is the memory of witnessing a man's death and seeing the woman as a child that allows the character to travel back in time without losing his mind.
With time travel theory, there are only two paths of logic: One is that a timeline cannot be altered. These scenarios must follow that logic because it involves a person going back in time and setting the course of events that eventually leads to them going back in time. These timelines cannot be logically altered because changing them would change the course of events and they would not wind up going back in time and setting off the course of events that eventually causes them to go back in time in the first place. Did I say that right?
The other path of logic is the parallel universe theory. When someone goes back in time and alters a timeline, this creates a parallel timeline, or universe. These scenarios can't occur because going back in time creates an alternate timeline which would not effect anything that happened in the timeline the traveler started from.
Okay, now I've confused myself.